Jay Cost at the Real Clear Politics HorseRaceBlog has some great analysis on the evaporation of Democratic support in Southern counties from 1996 to2008. At the same time the GOP has been losing support in the Northeast, the Democratic Party has been losing support in the South and South Atlantic. Check out the change in the maps between Clinton(96) and Obama (08). Jay Cost:

The bottom line is that Obama’s voting coalition is substantially less rural, less white, and less Southern than Clinton’s – leaving many House members in a difficult position vis-à-vis the party’s legislative agenda. Members like Boren now must choose between their party and their constituents.

Among the top of the list of Dems in Republican leaning districts are Bobby Bright (R +17) and Parker Griffith (R+15).